Apparatus for applying covers to containers



y 11, 1967 T. E. FORD APPARATUS FOR APPLYING COVERS TO CONTAINERS 3 Sheets-Sheet 1 Original Filed Feb. 7'. 1963 BY WW2 ATTORNEY July 11, 1967 T. E. FORD APPARATUS FOR APPLYING COVERS TO CONTAINERS 5 Sheets-Sheet 2 Original Filed Feb.

FIG-.4

INVENT OR 7 7afims 5. 6/20 ATTORNEY July 11, 1967 T. E. FORD APPARATUS FOR APPLYING COVERS TO CONTAINERS 5 Sheets-Sheet 5 Original Filed Feb' 7, 1963 .INVENTOR 7 E. Hm

BY W f 4 United States Patent 3,330,094 APPARATUS FOR APPLYING CGVERS T0 CONTAINERS Thomas E. Ford, Arlington, Mass, assignor to W. R.

Grace & (10., Duncan, S.C., a corporation of Connecticut Original appiication Feb. 7, 1963, Ser. No. 256,943, new Patent No. 3,257,769. Divided and this application Sept. 24, 1965, Ser. No. 505,218

4 Claims. (Cl. 53-329) This application is a division of my prior copending application Ser. No. 256,943, filed Feb. 7, 1963, and now Patent No. 3,257,769.

This invention relates to an automatic machine for applying covers to pies, pans of raised biscuits, sliced luncheon meats, tray packaged fruits, and vegetables. In an application, Ser. No. 81,191, and now Patent No. 3,120,728, filed by William T. Snow Jr., et al., a machine was disclosed which applies covers to pans, trays, or backing boards containing or supporting such products. The Snow device is not entirely automatic in that the covering film, before sealing, had to be manually placed over the goods to be packaged. For convenience and brevity, such goods will hereafter be called pies and their pans, trays, or supports will hereafter be called pans, and such meaning is intended in the following specification and claims.

The present invention is an improvement upon the Snow device. It provides means automatically to feed the covering film into the correct position to cover the pie, releases the film covering from the conveying means, shrinks the covers into sealing relationship with the rim of the pan and delivers the sealed product as a completed package at the takeoff station. Inasmuch as these means in the preferred example, hereinafter set forth, are designed to be used in conjunction with and in substitution for certain parts of the Snow device, the entire disclosure of the United States application Ser. No. 81,191, filed I an. 6, 1961, is incorporated herein by reference.

The improvement by which the automatic functioning of the pie covering machine can be secured depends upon the discovery that films which have high shrink energy can be gripped frictionally at their lateral margins and that when such a film is subjected to heat in areas adjacent to those margins, the extreme shrink of the film snaps the sheet out from its frictional engagement and throws the film rather forcibly towards its center. In consequence, it is possible to pinch the film between pairs of upper and lower moving belts, cause these to transport the film and lay it in proper position over the pie. Then when hot air, flowing upwards through special, marginal oven vents, strikes the under surfaces of the film, the film is heated, shrinks near its lateral margins, pulls itself free of its support and tacks itself beneath the margin of the pie pan adjacent the transverse radius of the pie.

Thereafter, with slight modification, the invention disclosed by Snow et al completes the sealing of the cover about the rim of the pie pan.

The primary objects of this invention are to make the sealing and packaging of bakery products and grocery items an entirely automatic procedure and to provide apparatus for such operations. These and other objects and advantages will become apparent from the specifications and from the accompanying drawings wherein FIGURE 1 is a side elevation of the machine With some parts broken away and certain of the parts in section for better illustration;

FIGURE 2 is a top plan view of the oven openings;

FIGURE 3 is a top plan view of the machine with certain parts broken away for better illustration;

FIGURE 4 is a vertical section of the apparatus taken on line 4-4 of FIGURE 1.

FIGURE 5 is a detail perspective view of the holding and transport belts which apply the covering to the containers;

FIGURE 6 illustrates the completed, covered pie as it nears the takeoff station; and

FIGURE 7 is a magnified cross section of the overhead pressure belt preferably used in the invention.

The packaging apparatus 10 comprises two (or more) elongated beam members 11 and 12 supported upon a plurality of legs 13-13, five of which are shown in FIGURE 1. Two (or more) subsidiary beams 14 and 15 stretch longitudinally between the outside legs and ofier support for the drive motor 16 and the oven fan and fan housing 17. A foraminous conveyor belt 18 is supported between the beams 11 and 12 and is operatively connected to be driven from the motor 16 or other suitable power source.

A plurality of vertical supports 19, 20, 21 and 22 are secured to the upper frame members 11 and 12. These are shown in FIGURES 1 and 3. Drive roll 23, which derives its power by connection between it and the roll 24 of the forarninous belt, is journalled between the supports 19 and 22. Journalled between supports and 21 is a shaft 81 upon which are mounted idler rolls 25 which in turn support a slack running heat resistant belt 26. As a best seen in FIGURE 7, the belt 26 actually is comprised of a wide belt of heat-resistant rubber 26a and a narrower belt formed of wire links 26b. The wire belt runs underneath the rubber. It is essentially the same length and is equally slack. Its function is to prevent the exceedingly slack rubber belt from slipping. Inasmuch as both belts run together and act as a unit, they will hereafter be referred to as slack belt 26. The lower flight, 27, of the belt is extremely slack. It normally falls into contact with the foraminous belt 18 and so rests and presses upon any article passing between belt 18 and itself.

Iournalled in and extending transversely between stanchions at the end of beams 11 and 12 are a pair of drive rolls 28, 29 which secure power from the common power source, e.g., motor 16. These rolls drive two pairs of endless carrier belts 3334 and 33a3-sa which run over the idler rolls 35 and 36 jornalled between supports 19 and 22. The carrier :belt pairs lie on either side of and thus do not interfere with the travel of the slack belt 26. Suitable gears, drive belts, etc. are provided as necessary to drive the foramious conveyor 18, slack belt 26 and belt pairs 33-34, 33a34a at essentially the same speed and in such manner that the pans film cover sheet and the slack belt lying thereover travel in the same direction.

Instead of merely placing the pie plate at random on the foraminou belt as in the Snow device, foraminous belt 13 carries at spaced intervals a number of pie pan holders 37 or jigs each adapted to receive a pie plate.

The jigs 37 are loaded with pies at a loading station 38, located at far right end of FIGURE 1. The pie loader is not part of the invention but may be a sweep-arm device operated by a Geneva cross motion and timed so that a pie is loaded with each arrival of successive jigs at station 38.

A sheet-feed device, not part of this invention, takes sheets from a supply stack located on the right end of the machine and delivers single sheets to the nip between the carrier belt pairs in such a manner that each lateral edge of the sheet is gripped between a pair of carrier belts while the leading and trailing edges of the sheet remain free.

Foraminous belt 18, slack belt 26, and the carrier belt pairs all run at the same surface speed, and since the sheet feeder is timed to insert a sheet in the nip at the proper time sequence, a pie on jig 37 and the covering sheet 41 enter the oven together, with the sheet extended above and completely covering each pie (see FIGURE 5).

Pressure shoes and 31, supported from the Wall of the oven (see FIGURE 4) and extending for a distance to adjust the bite of the belt pairs.

FIGURE 2 shows in detail the openings in the oven floor through which hot air is blown upwards against the under surface of the covering sheet of film. As seen in this figure together with FIGURE 5, the slack belt 26 drapes over the pie and forces the sheet of film 41 into contact with the rim of the pan at the leading and trailing points on its periphery. Consequently, the top of the pie is shielded from heat and only the margins of the covering film 41 which are exposed beyond the rim of the pan are heated by the up-fiowing hot air. The shrinkage which follows as a consequence of heating, locks the sheet 41, or tacks it under the pan rim at its leading and trailing points.

As the heating continues in the first oven stage, the lateral shrinkage in the exposed areas rises. Then, as the extra pressure between the belts relaxes, since the belts have now moved beyond the pressure shoes 30-31, the inward pull is now so large that the sheet is pulled toward the center of the oven from between each pair. of carrier belts, actually snapping rather forcibly as it leaves their grip. The area which was held between the belts and hence is substantially unshrunk snaps against the pie plate and beneath the rim. The continuing shrinkage shrinks the lateral marginal areas of the sheet, which are now free,

into a lock-under or tacking position beneath the rim of the pan adjacent its transverse diameter.

The advance of the carrier then carries the pie to position 2 in the oven where'the under side of the sheet is exposed to air entering through the wide openings 45 and 46. As a consequence of this heating, the entire exposed area of the cover shrinks in under the rim of the pie plate. The carrier then moves the pie over the outlet of the cooling fan 50 and then through the heating oven 48, which directs hot air on the top surface of the covered pie and shrinks the cover tightly over its entire extent.

In order for this equipment to be operative and permit the release of the covering material from between the carrier belts, shrinkablefilms having high shrink energy are necessary. Such filmmay include various types of heat-shrinkable, plastic films in thickness between /2 and 5 thousandths of an inch. Among such may be mentioned stretched films of rubber hydrochloride, stretched films ofvinylidene chloride polymers, stretched films of polystyrene and films of analogous materials which have the necessary mechanical characteristics. But, because of its low cost and of its high tensile strength and very high shrink energy, I prefer to use irradiated polyethylene, which, subsequent to irradiation, has been stretched in both directions at least 350%. Irradiated, biaxially oriented polyethylene has high'shrink energy, i.e., from 100 to 500 p.s.i. at 96 C. Shrink energy is the force of contraction at a given temperature when the material is restrained and, more specifically, it is the measurable tension in a fully mono-directionally restrained strip of film when the film is heated to the specified temperature.

I have used, successfully, as the base material of the film, Alathon 14, having an average molecular weight of 20,000, a density of 0.914 and a melt index of l.8which has been irradiated to an extent of about 12 megarads and then has been stretched biaxially 350% in both lateral and longitudinal directionsthe finished thickness of the film was1 /2 mils. This material possesses the shrink energy of aboutl50 p.s.i. in both directions at 96 C. The irradiation may be accomplished in a conventional manner, e.g., by the use of electron beam generator such as the 2,000,000 volt General Electric Resonant Transformer Unit, or a Van de Graafi Electron Accelerator operating at approximately 2,000,000 volts with a power output of 500 watts. Other radiation sources, such as cobalt 60, may be employed provided equivalent total dosage 'is given. Biaxial orientation may be accomplished by forcing air into a heated tube of polyethylene to form a bubble which is then trapped between two sets of pinch rolls. As the air enters, the tube of polyethylene undergoes both radial and longitudinal stretching to' accommodate the air bubble. Trapped between the pinch rolls, the bub-' ble rides through the whole length of the extrusion, stretching the polyethylene both laterally and longitudinally and simultaneously thinning the extrusion to film thickness.

If a round pie is to be covered, square sheets of such material as has been described are preferred, for then, the four corners do not entirely disappear into the peripheral seal, but leave four pull tabs 58 (FIGURE 6) which in the case of 8- and 10-inch pies, are large enough to be grasped between the thumb and forefinger. Anyone of these may be pulled to loosen and remove thecovering.

Save for the oven floor with its special apertures, the general design of the oven follows the re-circulating hotair design disclosed in the Snow et al. application. Space must be left between the oven wall andthe carrier belts to provide a passage for the upward flow of air between the belts and the oven walls in the initial heating stage. (The air-fiow pattern isshown by the arrows in FIGURE 4.)

Thereafter, the air flows upward and escapes through the oven roof vent 51 into the duct 52, which leads to the fan intake 53. From the fan the air is forced upward into a plenum chamber 55, where the flow divider 57' directs its flow towards the several apertures in the oven floor, thus completing the circuit.

The remaining path of the pie through the apparatus also follows the Snow et al. design. As soon as the pie leaves the oven, it is bottom-cooled by passing over the cold air flow directed through the foraminous belt 18, by the cooling fan 50. Cooling chills the peripheral seal and makes it possible for the seal later to withstand the pull which is developed when the entire pie covering is topshrunk as the pie passes through the final heating chamber 48.

The apparatus has a high throughput and delivers securely sealed pies and other pan or tray packaged products without the need of a special operator.

I claim:

1. Apparatus for sealing a shrinkable film cover over a pie contained in a pan comprising 'a conveyor having pan-receiving mean arranged at uniformly-spaced intervals about said conveyor, transport means arranged parallel to each margin of the conveyor adapted to frictionally engaging a covering film and to move and maintain a cover over each pie, 'a slack running, flexible belt suspended above but normally in contact with the conveyor and under which the covering film and pie pass,

second set of openings in communication with the heat source to direct heat about the periphery of a pie pan.

2. Apparatus according to claim 1 wherein the slack belt comprises a belt of a heat-resistant rubber and a narrower, under-running belt of substantially equal length formed of wire links, whereby both belts move together as a unit and slipping of the slack belt on the. drive roll is prevented. a

3. Apparatus according to claim 1 wherein the fri e tional engagement exerted. by the transport belts is adjustable and adjustment is secured by belt tensioning means. .4. In a machine of the class described having a pie transport carrier and an oven wherein a heat-shrinkable film covering may be shrunk into engagement with the periphery of a pie pan, means to receive and to transport a film covering and maintain said covering in position over a pie including two parallel pairs of belts, each of said pairs being adapted to enagage the covering sheet between the inbound flights of each pair adjacent the lateral rnargin of the sheet, power means to drive the pairs of belts and the carrier at the same linear speed and thereby maintain the cover centered over the moving pie, and heat- 10 ing means within the oven arranged to heat the film in strips adjacent each of the carrier belts and thereby cause the film to shrink transversely, pull loose from the carrier belts and engage the rim of a pie pan at points adjacent the intersection of its transverse diameter with the rim of the pan.

References Cited UNITED STATES PATENTS 3,014,320 12/1961 Harrison 53-42 3,071,905 1/1963 Morse 5330 X 3,120,728 1/1964 Snow 53-42 ROBERT C. RIORDON, Primary Examiner. R. L. FARRIS, Assistant Examiner. 

1. APPARATUS FOR SEALING A SHRINKABLE FILM COVER OVER A PIE CONTAINED IN A PAN COMPRISING A CONVEYOR HAVING PAN-RECEIVING MEANS ARRANGED AT UNIFORMLY-SPACED INTERVALS ABOUT SAID CONVEYOR, TRANSPORT MEANS ARRANGED PARALLEL TO EACH MARGIN OF THE CONVEYOR ADAPTED TO FRICTIONALLY ENGAGING A COVERING FILM AND TO MOVE AND MAINTAIN A COVER OVER EACH PIE, A SLACK RUNNING, FLEXIBLE BELT SUSPENDED ABOVE BUT NORMALLY IN CONTACT WITH THE CONVEYOR AND UNDER WHICH THE COVERING FILM AND PIE PASS, POWER MEANS TO MOVE THE CONVEYOR, THE TRANSPORT MEANS AND THE BELT AT IDENTICAL LINEAR SPEED, MEANS DEFINING SEPARATE OPENINGS ADJACENT THE UNDER SIDE OF THE CONVEYOR AND IN COMMUNICATION WITH A HEAT SOURCE TO DIRECT HEAT AGAINST THE EXPOSED AREAS OF FILM ADJACENT EACH LATERAL MARGIN AND CENTRALLY OF THE SHEET, AND MEANS DEFINING A SECOND SET OF OPENINGS IN COMMUNICATION WITH THE HEAT SOURCE TO DIRECT HEAT ABOUT THE PERIPHERY OF A PIE PAN. 